The present invention relates generally to the field of wood chip processing, and more particularly to a machine and associated method for dense loading of containers with wood chips.
One major factor in the cost of wood chips for paper making is the cost of transporting the wood chips from the chip manufacturing site to the paper mill. The wood chips are typically transported in rail cars, but may also be transported in barges, trailers, or the like. Typically, the transportation costs are based primarily on the number of containers used to ship a given load of wood chips. As more densely packed containers means that fewer containers are required to ship a given amount of wood chips, it follows that more densely packed containers will generally supply more useable wood chips to the paper mill at a lower transportation cost.
In view of this cost dynamic, there has been substantial effort over a long period of time to develop dense packing techniques. For instance, several prior art techniques feed wood chips to a distribution element that spins about a vertical axis. Such devices are shown, for instance, in U.S. Pat. No. 5,735,319 to McNamara et al. and in U.S. Patent Application Publication US2002/0076308 to Bailey et al. Such techniques tend to output wood chips in a circular pattern, which is less than ideal for some containers, such as rectangular railcars. Further, such techniques are limited in many situations to an increase in packing density of typically not more than 17% over conventional free-fall
Accordingly, there remains a substantial need in the industry for alternate wood chip loading techniques, preferably techniques that produce non-circular output patterns and/or higher packing densities.
A wood chip loading device of the present invention loads wood chips into a container with a density greater than that achieved using conventional free-fall techniques. Preferably, the device packs the wood chips at a density that is at least 25% more than that achieved with the conventional free-fall techniques. Due to this higher packing density, the cost of shipping the wood chips is significantly reduced.
In one embodiment, the wood chip loading device includes a drum rotating about a generally horizontal axis. The drum includes a plurality of outwardly extending blades that act to fling the wood chips out so as to land in a landing zone that is less than semicircular, and preferably generally in the shape of a truncated sector of 1xc2x0-30xc2x0 in arc, and more preferably in a generally rectangular pattern. The output of such a device may be used to form a stack of wood chips in a transport container such that the wood chips have a substantially uniform orientation therein, thereby allowing for greater packing densities.
Some embodiments of the present invention include a feed chute assembly that allows for adjustment of the ratio of the input stream that is delivered to the middle and side portions of the spinning drum. In some of these embodiments, this adjustment may be made while the device is operating, thereby allowing for xe2x80x9con-the-flyxe2x80x9d adjustments by the operator.